Reality: It’s all in your head

Image: Uwi Heine Debroedt

ONE of the most fundamental questions of philosophy – a fundamental question of human existence, actually – is whether or not there is a reality that exists independently of our perception. Even though it is a profound question, it is in a sense a relatively easy question to answer. But of course, that hasn’t stopped generations of philosophers of every stripe from grappling with it.

There are two basic ways to view reality. Realism, which can be broadly categorized into metaphysical or scientific realism, is a thesis that objects, properties, and the relationships among them exist independently of our perceptions or beliefs about them. The difference between the two forms is that metaphysical realism does not necessarily entail that those constituents exist in the forms defined by science. Anti-realism is the opposite: Reality is not independent of our conceptions or perceptions of it; for all intents and purposes, anything that we cannot imagine or measure does not exist. Realism, specifically metaphysical realism, among other things is the basis for religious belief.

Between the two, anti-realism is the only one that makes any sense. After all, the very definition of “reality” is a human construct; reality relies on our relating to it in some way, which we do, even if we take a position that “reality exists independently of the human mind,” we are still describing it in a human-relative way.

But anti-realism is still imperfect; we have several millennia of human history in which our knowledge of the world has broadened and evolved as we have discovered new things that we did not know before as evidence of that. Up until a little over a century ago, that history tended to support the realist perspective. Quite obviously, our discoveries did not cause the genesis of things, but rather revealed to us things that had always been there; electrons, for example, did not suddenly spring into being when J.J. Thompson figured out cathode rays must be made up of individual electrically-charged particles (which happened in 1896, for those of you keeping score at home).

Or did they?

As physics has advanced into the quantum realm and we have drilled deeper to find the fundamental constituents of…well, everything, we have gone far beyond the extreme minimum scale at which we can tangibly detect something with our natural senses. We can’t see an electron – or a quark, or a boson, or a neutrino, or a photon, any of the 17 fundamental particles which, as far as we are concerned, make up everything in this universe. We can build sophisticated, powerful equipment to detect the presence of electrons, create streams of them, or trap a single electron; some years ago, scientists in Sweden even managed to create a video of the motion of an electron. But we can’t actually see the electron; the best we can do – and as far as we know, the best we will ever be able to do – is to see its effects, and infer its existence and properties from those.

Put another way, what we are detecting or creating beams of is a something of our own design – an electron is what it is because we walk backwards from the effects of its presence to define it in terms of various mathematical formulae. The cognitive model thus created agrees with the effects we observe, the models we’ve created at larger scales (such as the behaviors and properties of atoms), and the effects we expect from experiments. Ergo, electrons exist and are a part of reality, even though we will never actually see one or know exactly what it is based on our own five senses.

In their 2010 book The Grand Design, Stephen Hawking and Leonard Mlodinow introduced a concept that explains all this, an idea they called model-dependent realism:

“…the idea that a physical theory or world picture is a model (generally of a mathematical nature) and a set of rules that connect the elements of the model to observations. This provides a framework with which to interpret modern science.”

All we can know of reality is what the network of these world-pictures that we have created tell us. The concept of model-dependent realism does not require that a particular world-picture be unique or even complete; two different theories that explain observations of the same thing equally well are equally valid. This is a form of ontological pluralism (one that becomes very important in the next part of this series) that Hawking and Mlodinow neatly explain with an amusing analogy:

A few years ago the city council of Monza, Italy, barred pet owners from keeping goldfish in curved bowls. The measure’s sponsor explained the measure in part by saying that it is cruel to keep a fish in a bowl with curved sides because, gazing out, the fish would have a distorted view of reality. But how do we know we have the true, undistorted picture of reality?

The goldfish view is not the same as our own, but goldfish could still formulate scientific laws governing the motion of the objects they observe outside their bowl. For example, due to the distortion, a freely moving object would be observed by the goldfish to move along a curved path. Nevertheless, the goldfish could formulate laws from their distorted frame of reference that would always hold true. Their laws would be more complicated than the laws in our frame, but simplicity is a matter of taste.”

The concept of model-dependent realism doesn’t explicitly reject metaphysical realism – the notion of reality independent from the human mind – but rather asserts that our reality is fundamentally conceptually relative:

According to the idea of model-dependent realism…our brains interpret the input from our sensory organs by making a model of the outside world. We form mental concepts of our home, trees, other people, the electricity that flows from wall sockets, atoms, molecules, and other universes. These mental concepts are the only reality we can know. There is no model-independent test of reality. It follows that a well-constructed model creates a reality of its own.”

Expressed a slightly different way, there is no such thing as a reality that we cannot conceptualize; even if such a reality were possible, it would be completely irrelevant to us, forever existing beyond our infinite potential for imagination.

Life, the universe, and everything exists, in the only way that matters, in that wonderful place we call the human mind. Our reality is one we create, which grows and evolves as our capacity to grasp and define its complexity expands, but ultimately can never be bigger than we are.